The invention relates to a windshield wiper arm in which the link may be swivelled from an operating position to a tilted position.
Motor vehicles are increasingly equipped with wiper systems in which the windshield wiper is parked in a slot between the windshield and the engine hood. However, only a limited angular range is available for tilting the wiper arm from the operating position into the tilted position. Most of today's wiper arms cannot be used for windshield wiper systems of this kind, because the angular range between the operating position and the tilted position is too large. The reason is that in such wiper systems the link and the wiper rod have to be swivelled relative to the fastening member so far that the connecting line between the fixed suspension points of the tension spring on the wiper rod and on the fastening member crosses the axis between link and fastening member such that the dead center of the contact pressure spring relative to this axis is overcome.
German petty Pat. No. 1 774 020 shows a wiper arm in which, when the link is tilted, the point of application of the tension spring on the fastening member is adjusted relative to the articulated axle. The tension spring acts upon a pin which is displaceably guided in a straight longitudinal hole on the fastening member. Compared with constructions having a stationary holding pin, the required tilting angle is diminished by displacement of this pin because with a displacement of this pin the perpendicular spacing between the articulated axle between fastening member and link and the action line is reduced. However on disadvantage in this construction is that a distinct locking point cannot be felt between the operating position in which the link is drawn towards the window pane, and the tilted position in which the link is prestressed in the opposite direction. One reason is that during a first swivelling range of the link from the operating position, the holding pin initially retains its first end position until the action line of the spring element adjusted to be approximately perpendicular to the longitudinal hole. In a following swivelling range the pin is then displaced in the longitudinal hole, whereby the tension spring is only slightly tensioned. The action line of the tension spring cuts the articulated axle at exactly the time when the pin occupies its other end position. The link must be swivelled by a further amount so that the tilted position is sufficiently stable.
Although the tilting angle is limited in comparision with prior constructions having a fixed point of application of the tension spring, it nevertheless does not meet requirements for such devices. Moreover, the locking point cannot be distinctly felt. Furthermore, because of friction losses between the pin and the longitudinal hole and because of possible dirt in the longitudinal hole it can not be ensured that the pin really reaches its other end position.